The invention is directed to apparatus for the production of a packaged unit made up of a plurality of layers of similarly shaped items stacked one layer on another and completely enclosed by shrinkable foil. In forming the stack, the layers have a similar make-up, however, the final layer is inset from the subjacent layers on at least two opposite sides forming two parallel spaces for receiving support members of a lifting device. A first shrinkable foil is placed over the entire stack and by applying heat the foil is closely shrunk about the stack. Next, the stack is inverted through 180.degree. so that the inset final layer is located at the bottom of the stack. A second shrinkable foil is placed over the stack and is shrunk about it by applying heat.
In a known device (DE-PS No. 27 43 562), the shaping tools are located in a turning device and are formed as a two-part relatively complicated shaping frame. Prior to the entrance of a stack along with a first heat shrinkable foil positioned on it into the frame, the stack is moved to one of two conveying surfaces of the turning device. After the arrival of the stack with its first shrinkable foil, the shaping tools are moved from above into the inset spaces of the final layer of the stack during the closing movement of the two conveying surfaces of the turning device. After the stack has been turned, the shaping frame is removed from the turning device and is conveyed along with the stack through a device for applying a second heat shrinkable foil and a second shrinking device. The shaping tools are then separated from the stack and returned to the turning device. While this known device is very favorable for forming non-deformable and stable stacks, it is, however, very expensive and requires considerable space for the overall arrangement.
Furthermore, it is known in DE-PS No. 27 60 249 to position the turning device between a device for applying a single shrinkable foil and a single shrink device where there is a small output requirement for reducing the equipment expense whereby after the first shrinkable foil has been applied, the stack merely passes through the turning device without being inverted so that the first shrinkable foil can be shrunk-on in the shrinking device. Next, the stack is returned to the turning device where it is inverted and then moved back to the shrinkable foil applying device where it is covered with a second shrinkable foil. Again, the foil enclosed stack is passed through the turning device and is conveyed into the shrinking device where the second shrinkable foil is shrunk-on. To shape the inset spaces in the stack, this known device requires two additional shaping devices, one located upstream of the shrinking device for shaping the inset spaces, if the spaces are located at the top, and one downstream of the shrinking device for shaping the inset spaces if they are located at the bottom after the stack has been inverted.
In another known apparatus, disclosed in DE-OS No. 27 02 613, it is known to move the narrower final layer located on a floor mounted conveyor against a stop on one side by lowering the stack in an appropriate region of the conveyor to assure the shaping of the bottom layer with its inset spaces and to shape the opposite side of the layer by pivoting a pressure flap into contact with the layer.
Another known apparatus for shaping the inset spaces in the bottom stack is disclosed in DE-PS No. 28 39 089. In such apparatus, after the stack leaves the shrinking furnace with the shrinkable foil hood partially drawn into the inset spaces, the stack is further moved on a conveyor to a station containing sets of rollers arranged to enter the inset spaces. The sets of rollers are used as conveyor elements, the stack is placed on a lowerable section, and the section is lowered by the dimension of the rollers and the rollers move into the inset spaces with the stack being moved downwardly to an extent such that the sets of rollers press the shrunk-on hood against the bottom layer of the stack. In U.S. Pat. No. 4,724,652, another apparatus is disclosed in which a single shrinking foil application device and a single shrinking device form a combined arrangement. Shaping tools in the form of conveyor elements are incorporated into an inverting unit adjacent the combined foil applying and shrinking units. The conveyor elements are movable into a shaping position in inset spaces of a stack by a drive unit associated with the inverting unit after the stack has been inverted. Subsequently, the stack is returned to the combined foil applying and shrinking units where a second shrinkable foil is placed over the stack. Again, the stack is returned to the inverting unit to shape the foil in the inset spaces. After the conveyor elements are removed from the inset space, the stack is moved out of the inverting unit. Such an apparatus affords a reduction in the required space and in technical resources. In certain circumstances, however, due to the location of the conveyor elements shaping the foil, it may not be possible to provide an acceptable shaping of the foil in the inset spaces because the foil has been cooled as it moves from the combined units to the inverting unit. As a result, the foil tends to stretch diagonally across the insets spaces and may be damaged by the shaping tools or conveyor elements. The effect of such condition varies dependent on the type of shrinkable foil used.